Electrical switch mechanism



June 10, 1952 J PAVlTT 2,599,657

ELECTRICAL SWITCH MECHANISM Filed March 8, 1950 5 Sheets-Sheet llllllmllmmllll 30' p 3 Al'o ey June 10, 1952 VlTT 2,599,657

ELECTRICAL SWITCH MECHANISM Filed March 8, 1950 a Sheets-Sheet 2Inventor June 10, 1952 F. J. PAVITT ELECTRICAL SWITCH MECHANISM 3Sheets-Sheet 3 Filed March 8, 1950 Inventor EVZ'ZLLL By 4.

A or ey patented June 10, 1 952 UNITED STATES PATENT OFFIEE FrederickMines l aeitt, Brighton,

signofr t6 Allen West and Company Limited,

Brighton,-'England, a British company Am li i i March 8; 1950,,serial/f.

I171 G eat Britain uar 28; ,1}?

(Ci. Mme-406) 13Clail'ii5'.

This invention relates to eiecti'icai switch mechanism and has for itsobiebt to pi'otii'dje an improved electrical switch mechanism of thekind which can be closed manually, tripped with a snap action manually,and tripped with a snap' aetion under faulty electric conditionsindependently of any man la] operation.

The invention consists broadly of an ele'etri cal switch mechanismcomprising a movableswitch element movable in one direction to theclosed position of the switeh and in the other qirection to the openposition of the switch and biased-tome open position of said switoh,

an' actua'ting element movable to an operative position anti returnableto a non epe'ratii e positi'on; a lever pivotably mounted between itsentis' onsa'id aeti 'ating element, a tripping ele-- ment 'whieh ispositioneei according to the elec-' trical conditionsfin thecireuiteontrplle'd by said switch, said; tripping element having a no fn al'p'o'sitior whioh it beoup'ies when said circuit conditions alitfi f l lQl ma'l' and -a tripping Dosition whic'h -it open Les when said ci'riiiton 'en ar ab mal y the ef t e m h i ing such that, when said actuatingeleii ent is moved to the operative position, said tripping element,tang at the no 'fnai position; jretains one end of said ie' vei' whereby"the otheii' end moves and engages said "switch element and conveysit'to the -ciosed position of the fiwi teh, and,-upon said tripping1neving to the tripping position, *i't eieases the first-flamed end ofsaid leven whereupon said switch 'elemerit-is {freeto -enim to the {openposition oi. the svvi'teh thereby rotating the deter mm its pivot.

Tn order that-the invent-ion maybe the more clearly understood a=switchmechanis'm aeeo'rdance' therewith will -now =be described, referencebeing "made to the --accompanying =diaw in'gs wherein g Figure 1 is :a"front -e1e"vation'-o'f said me-ch III 2 partly insection-approximatelyon the line VII"- VII of Figure '3'; t Figure 8 is a fragmentary viewshowing certain of the parts when at the tripped position.

Referring to the drawings the switch is a three phase switch eeinprisingthree pairs of fixed contacts I and three bridging contacts 2. 'Ifhebridging eontaetsf are mounted in spaced relation along contact carrying bar 3 each bridging eontact being transverse to thebai and"projecting on each side thereof. sam a? s s iohgi-tudinaily' s ame toand from closed petition at which theend's of each bririg ing contact 2engage its respeetiv'epair Qf'fixed e'entaets and a'iiflopenpo'sition.(illustrateii' in Figi'n'e 2) at whichle'a'eh' bridging contact 'dis=engages iespective pair of fixed contacts.

trip plate has "an arm 6 extending ni'oreeor eiess" horizontally irom'(one edge ith'ereoi. isaid p ate is pivoted at its opposite edge at J.50 that said arm 6 can -moive up anti f'down', means areprevided,-{whiehwill be hereinaiiter deseiibed, iivhei'eby {so dong .asthe windings" 4 are ene'i' gised but' notTovermaded .said .lrip piatea'ihas its ari'n fi dQWmbixtiflah overload or voltage =-fai1=ure oecu rs inany mindihgkaiii tiip --piate is =r'alised to the up (position of isalidarm 6. Means are -.pi ovided, however, which will "be -hereinafterdescribed, whereby" Inormally when the-switc'h is notiin iu'sei'saidtrip plate :5 -remains \with iitss'arin 16 at the aiiiwn position. I

A -sta' t Apiate ='8" is provide in 5a iveirtie'alp ajneparallelto-thepontaefiarryim barl3na'nd said start plate is horizontallysiidableiniits own plane. Saidr'start Iate-sIi isiispringgbiased in thesame :dire'etionaassaidehorikoiital -\;bar'=' 3, i.-e. to the- -i ightaccording toFigure'sB. anti-4.

-=A 'leve'r 9 is mounted Ion :said staftpIat 1'8 so' as to pivot about a-horizontal axis 10' ctr-ansverse to said sta'rt lplate.cSaict;1eirei$-9.;compiises a lon'garm extendingupwardly.ltrom'itswpivot axism and said; long arm .at; its mpperiend satires 3 and 4) of the aforesaid arm 5 of the trip plate 5. Said lever 9also comprises a short arm extending to the right from its pivot axis,and said short arm terminates in a downwardly extending hook portion 9b.

To close the switch, the start plate 8 is pushed to the left (accordingto Figures 3 and 4) in opposition to its spring bias. The upper end 9aof the lever 9 is retained by its engagement with the arm 6 of the tripplate 5, but

the lower end of said lever 8 is carried to the left with the startplate 8. When the start plate 8 has reached a given point in its travelto the left, the hook portion 91) of the lever 8 engages a horizontallateral projection 3a from the contact-carrying bar 3, and thereaftersaid contact-carrying bar is carried to the left with said start plate.When the bridging contacts 2 have reached the closed position, saidstart plate 8 is latched against return.

The switch is now closed and the position is as in Figure 4. The longarm of the lever 9 is inclined to the right, and the short arm with thehook portion 53b is inclined downwardly. If overload or voltage failuretakes place, the arm 6 of the trip plate 5 will be lifted, and will riseclear of the upper end 9a of the long arm of the lever 9. This leavessaid long arm free to move to the left, and accordingly the short armwith the hook Sb to move to the right and upwards. Under the influenceof the bias on the contactcarrying arm 3 this movement of the lever 9takes place until the hook portion 91) is clear of the lateralprojection 35:. on the contact-carrying bar 3, whereafter saidcontact-carrying bar springs freely to the fully open position of theswitch. The lever 9 is now at a limiting position with its long arminclined to the left and its short arm with the hook Qb inclinedupwards. The start plate 8 is still latched at its left-hand position ofFigure 4. The relationship of the lever 9 and the lateral projection 3ais as shown in Figure 8.

The means by which the trip plate 5 is lifted in response to eitheroverload or voltage failure may be substantially the same as thosedescribed on my prior Patent No. 2,431,886 granted December 2, 1947.That is to say the windings 4 have dash pot controlled plungers H whichare lifted by overload and thereby lift said trip plate 5 which overliesthem, and also have no-volt armatures I2 which rise under spring biasunder conditions of no-voltage and thereby, again, lift said trip plate5 which overlies them.

In order that the trip plate 5 shall remain at the down position whenthe switch is not in use, a pivoted holding plate i3 is provided pivotedabout the same axis I as the trip plate. This holding plate overlies theno-volt armatures l2 and is normally spring biased downwardly so as tohold said no-volt armatures down against their bias when the switch isnot in use.

The means for latching the start plate 8 at its left-hand positionconsists of a stop-and-reset element M which pivots about a fixed axisit transverse to the plane of said start plate. This stop-and-resetelement has two arms Ilia, Mb projecting to the left one above the otherand it is biased clockwise, i. e. the said arms are biased upwards. Thestart plate at its upper edge has a horizontally bent-over lug 8a whichoverlies the upper edge of the lower arm Mb of the stop-andreset elementl4 and thereby limits the clockwise movement of the latter. The upperarm of said stop-and-reset element is immediately underneath theholding'plate l3. Said stop-and-reset element also carries a leaf spring16 projecting to the left above the holding plate.

When the start plate 8 is at its oif or righthand position, saidbent-over lug Ba of said start plate retains said stop-and-reset elementso far counter-clockwise that its upper arm is clear of the underside ofsaid holding plate l3 and said spring l6 presses said holding plate tothe down position. This is the position of Figure 3. When the startplate 8, in moving to the left, reaches the closed position of theswitch said bent-over lug 8a reaches a downwardly stepped portion Mc ofthe lower arm of said stop-and-reset element M, and consequently thelatter is capable of rotating a given distance in the clockwisedirection to the position of Figure l. The start plate 8 is now latchedby the step at Me against return movement, and also the spring it hasmoved clear of the holding plate 13 and the upper arm I ia of saidstop-and-reset element has moved far enough up to lift said holdingplate clear of the n-o-volt armatures. Thus, the no-volt armatures I2are free to lift the trip plate 5 and cause the same to exercise itstripping function and, at the same time, the start plate 8 is latched atits left hand position. It will be seen that if, in the intervalsubsequent to the closure of the switch contacts I, 2 and prior to therelease of the no-volt armatures i2, a heavy overload should occur, theoverload plungers I! will be free to rise and lift the trip plate,despite the fact that the no-volt armatures are still held down.

Assuming that the switch has been tripped by overload or phase failureas heretofore described, the starting plate 8 will be still latched atthe position of Figure 4 and. the correlation of the lever 9 and theprojection 3a will be as in Figure 8. In order to reset the mechanismfor enabling the switch to be again closed, said stop-and-reset elementi i is rotated counter-clockwise by hand. This moves the step 140 on thelower arm 14b of said stop-and-reset element clear of the bentover lug80. on the start plate 8, so that the latter can spring back to theright-hand position. At the same time the upper arm Ma of thestop-andreset element i4 and also the spring I6 move down and theholding plate is again returned by the spring iii to its down position,and, the bentover lug 8a on the stop plate being now at the right-handposition, the stop-and-reset element It will be prevented from returningclockwise, so the holding plate will remain down.

The start plate 8, in returning to the right, carries the lever 9 withit. Said lever first moves with its orientation unchanged (1. e. withits long arm inclined to the left and its short arm inclined upwardly)until the hook portion 9?) has passed over the lateral projection 3a onthe contact-carrying bar 3. Just after this a downward tail projectionat the lower end of said lever to the left of the hook portion 9bengages said projection 3a and consequently said lever 9 is turned in aclockwise direction about its pivot point Ill until its long arm isupright 0r inclined a little to the right and the short arm ishorizontal or inclined a little downwardly. During this movement theupper end of said long arm rides under the arm 5 of the trip plate 5,temporarily lifting said arm 6. The hook portion 9b moves down intoposition to the right of the projection 3a on the contactcairrying bar3. The switch is thus now fully rese Assuming that the switch is closed,to open it voluntarily the stop-and-reset element I4 is moved by handcounterclockwise as before, and

this, as before, win o'er it the start plate..8 to spring back to theright hand position, and win cause the holding plate I3 to be presseddown by means of the spring it. As this latter takes place be'foretheswitch contacts I and 2 o'p'en there is no moment when the trip plate 5'is lifted. Consedue'ntly the upper end So of the long arm of the lever 9remains to the right of the arm 6 of the trip'plat'e, and thecontact-carrying arm 3simply moves to the right with the hook portiontbof the lever. Thus the whole mechanism is set for re closure by'thestart plate 8.

Describing how certain constructional details of the invention the fixedcontacts I are mounted on ajmain body I? of insulating material. Thecontacts I of the bottom row pass through to the front of the body llwhere they are fitted with connecting screws. H3. The contacts l' of thetop row are electricallyconnected to terminals It at the back or saidbody 51. Other terminals are inounted at' the back of said body side byside' with the contacts I of the bottom row. These terminals 26 passthrough to the front of said body where they are fitted with connectingscrews 2i. Ihe windings 4 are connected across the .respective pairs ofconnecting screws I8 and 2| at the front of the body ll, by conductors22 one of which is seen in Figure 5, and it will be seen that byconnecting the respective pairs of terminals l8 and 20 at the back ofsaid body in the three phases of the controlled circuit; circuit con"-nections will be completed through the windings 4 when the bridgingcontacts 2 are moved to the bridging position in contact with thecontacts I.

The contact-carrying bar 3 is slidable-in a guide groove in the back ofthe body H. The biasing of said bar 3 to the open position of thecontact 2 is effected by means of a coiled torsionlspring 23 mounted ina recess in the front of said body IT and having an extending arm 23awhich engages the end of said bar 3, as shown in Fi ures 2, 3 and e. Asshown in Figure 2 the arm 23a hooks round the end of said bar 3} andthus serves to retain that end of said bar within its guide groove. Forretaining the other end of said bar in its guide groove, the startplate, which slides against the front face of said body l'l, hasa reartail extension 8b which passes round from the front to the back" of saidbody where it overlaps said bar 3 asbestshown in Figure 2.

The'start plate t" is guided inits-sliding more rnent against the frontface of the body I? by means of locating studs 2s and 25' on" said frontface'engaging in cut -outs 28 and 27 in said start plate,- and also bythe tail extension B'b' engaging in'a groove 23 in'the front face ofsaid body; Said start plate is retained against said-front face of saidbody by means of a plate 2'9 secured against the front face of the body.

The plate 29 carries thethree windings t togetlier with the overloadplungers H, the novolt armatures l2 and the dash pots Si! by which saidoverload plungers are controlled. The'structurecarried by said plate 25is substantially as described in my Patent No. 143L886 aforesaidandformsjin itself, no part of the present invention. It is sufiicientto say that the vertical plates 31" are rigidly mounted in front of thewindings Q-and that the no-volt armatures I2 arepivoted on theupper'edg-es of said plates 3| and have tail extensions 32 which arebiased downwardly by means oftension springs 33 whose upper ends areconnected to said tail extensions and whose lower ends are connected topoints near the lower ends" or said' plates-i Thus the" xiii-voltarmatures 6 themselves are biased upwardly, and move-up;- wardly uponthe occurrence of voltages failure: The overload plungers H are biaseddownwardly by gravity and are raised upon the occurrence of overload.

The pivot axis 1 of the trip plate 5 soothe holding plate I3 isconstituted bya' length ofwire carried by the body I! as will b clea'rfrom the drawing. The arm 6 of said trip plate overlies the plunger Hand no-volt armature [2 of the centre winding t, and, in addition thereare we other arms 34 and 35 which overlie'the plung s II and no-voltarmaturs l2 of the other wi" ings A. Thus, as before stated; the tripplat 5 is lifted upon the rising of any'of the overload plungers or anyof the no volt armatures.

A common horizontally arranged tension can spring so serves both to biasthe start plate ilto its right hand position (according to Figures stopand reset element M in the and 4) and the clockwise direction. Thisspring 3'S'fat its' left' hand end is connected (as best shown inFigures 3 and i) to the forward end of the start plate8; and, at itsright hand and to the bottom of the stop-and reset element l4. p g

The lever 52 is guided in its travel byflbeing mounted between thes'tartplate 3 and th'e froiit face of the body it. The stopand-resetelement is mounteiion the body :7 as will be' iear' frdifi' the drawing.It consists ofa plate bentiri plan to U form, the arm Ma being on oneside of the U and the arm i on the'otlier.

In practice the whole mechanism may be e closed in a casing (not shown)which has" two push buttons mounted in one of its walls; start pushbutton which, on depression,- presses the start plate to the left byengaging the tail extension db, and a stop and-rese't push button whichon depression engages the stop-and r'ese't element is and rotates itcounter-clockwise.

I claim:

1. An electrical switch mechanism comprising an actuating elementmovable to an operative position and returnable to a non oper'ative'position, a lever pivotably mounted between its ends on said actuatingelement, a switch elementniovable along a given path in one direction toa s'witcli closing position and in the other direction to a.

switch opening position, means biasing said switch element to saidswitch-opening position; a tripping element having a normal position atripping position, means for maintaining said tripping element atsaidnormal position in re sponse to the electrical conditions in thecircuit controlled .by said switch being normal; and for moving saidtripping element to said tripping p'o? sition in response to saidelectrical conditions being abnormal, said tripping element, at its normal position, being located to engage and retain one end of said lever,upon said actuating element being moved from its inoperative to its'operative position, whereby the other end of saidle'ver is moved, andsaid other end being locatedto' en gagesaidswitch' element by suchmovemehtand convey it to the switch closing position, and said trippingelement; upon'moving to the tripping position, disengaging and releasingthe first named end of said 1ever,- whereby said switch elee ment' isreturned by said biasing means to said switch-opening position.

2. An electrical switch mechanism comprising an actuating elementmovable to an op'erativeposition and returnable to" a non-operativeposition; a lever pivotably mounted between, its ends on said" actuatingelement; a switch elementmounted independently of said lever formovement along a given path in one direction to a switch closingposition and in the other direction to a switch opening position, meansbiasing said switch element to said switch-opening position, a trippingelement having a normal position and a tripping position, means formaintaining said tripping element at said normal position in response tothe electrical conditions in the circuit controlled by said switch beingnormal, and for moving said tripping element to said tripping positionin response to said electrical conditions being abnormal, said trippingelement, at its normal position, being located to engage and retain oneend of said lever, upon said actuating element being moved from itsinoperative to its operative position, whereby the other end of saidlever is moved, and said other end being located to engage said switchelement by such movement and convey it to the switch closing position,and said tripping element, upon moving to the tripping position,disengaging and releasing the first-named end of said lever, wherebysaid switch element is released by said other end and returned by saidbiasing means to said switch-opening position.

3. An electrical switch mechanism comprising an actuating elementmovable to an operative position and returnable to a non-operativeposi-= tion, means biasing said actuating element to said non-operativeposition, a manually releasable latch for automatically latching saidactuating element at said operative position, a lever plvotably mountedbetween its end on said actuating element, a switch element movablealong a given path in one direction to a switch closing position and inthe other direction to a switch opening position, means biasing saidswitch element to said switch-opening position, a tripping elementhaving a normal position and a tripping position, means for maintainingsaid I tripping element at said normal position in response to theelectrical conditions in the circuit controlled by said switch beingnormal, and for moving said tripping element to said tripping positionin response to said electrical conditions being abnormal, said trippingelement, at its normal position, being located to engage and retain oneend of said lever, upon said actuating element being moved from itsinoperative to its operative position, whereby the other end of saidlever is moved, and said other end being located to engage said switchelement by such movement and convey it to the switch closing position,and said tripping element, upon moving to the tripping position,disengaging and releasing the firstnamed' end of said lever, wherebysaid switch element is returned by said biasing means to theswitch-opening position.

4. An electrical switch mechanism comprising an actuating elementmovable to an operative position and returnable to a non-operativeposition, means biasing said actuating element to said non-operativeposition, a manually releasable latch for automatically latching saidactuating element at said operative position, a lever pivotably mountedbetween its ends on said actuating element, a switch element movablealong a iven path in one direction to a switch closing position and inthe other direction to a switch opening position, means biasing saidswitch element to said switch opening position, a tripping elementhaving a normal position and a tripping position, means for maintainingsaid tripping element at said normal position in response to theelectrical conditions in the circuit controlled by said switch beingnormal, and for moving said tripping element to said tripping positionin response to said electrical conditions being abnormal, said trippingelement, at its normal position, being located to engage and retain oneend of said lever, upon said actuating element being moved from itsinoperative to its operative position, whereby the other end of saidlever is moved, and said other end being located to engage said switchelement by such movement and convey it to the switch closing position,and said tripping element, upon moving to the tripping position,disengaging and releasing the first-named end of said lever, wherebysaid switch element is returned by said biasing means to theswitch-opening position, and means whereby, upon said actuating element,subsequently to the return of said switch element to the switch openingposition in response to abnormal circuit conditions, returning to thenon-=operative position under its spring bias in response to the releaseof said latch, said other end of said lever engages said switch element,whereby said lever is returned to the position for its first-named endto engage said tripping element upon said actuating element being againmoved to the operative position.

5. An electrical switch mechanism comprising an actuating elementmovable to an operative position and returnable to a non-operativeposition, means biasing said actuating element to said non-operativeposition, a manually releasable latch for automatically latching saidactuating element at said operative position, a lever pivotably mountedbetween its ends on said actuating element, a switch element movablealong a given path in one direction to a switch-closing position and inthe other direction to a switchopening position, means biasing saidswitch element to said switch-opening position, a tripping elementhaving a normal position and a tripping position, means for maintainingsaid tripping element at said normal position in response to theelectrical conditions in the circuit controlled by the switch beingnormal, and for moving said tripping element to said tripping positionin response to said electrical conditions being abnormal, said trippingelement, at its normal position, being located to engage and retain oneend of said lever upon said actuating element being moved from itsinoperative to its operative position, whereby the other end of saidlever is moved, first and second projections formed on said other end ofsaid lever, said first projection being located to engage said switchelement, by such movement of said other end of said lever, and conveysaid switch element to the switch closing position, and said trippingelement, upon moving to the tripping position, disengaging and releasingthe first-named end of said lever, whereby said switch element isreleased by said first projection and is returned by its biasing meansto said switch-opening position, and means whereby, upon said actuatingelement, subsequently to the return of said switch element to the switchopening position in response to abnormal circuit conditions, returningto the non-operative position under its spring bias in response to therelease of said latch, said second projection engages said switchelement, whereby said lever is returned to the position for itsfirst-named end to engage said tripping element upon said actuatingelement being again moved to the operative position.

6. An electrical switch mechanism comprising an actuating elementmovable to an operative tion, means biasing said actuatingelementto'said non-operative position, a manually releasable latch forautomatically latching said actuating element at said operativeposition, a lever piviotably mounted between its ends on said actu-Iating element, a switch element-movable along a given path in onedirection to a switch closing position and. in'the other direction to aswitch opening position, means biasing said switch element to saidswitch opening position, a tripping element having a normal position anda tripping position, means for maintaining said tripping element at saidnormal position in response to the electrical conditions in the circuitcontrolled by said switch being normal, means for moving said trippingelement to said tripping position in response to no-volt conditions insaid circuit, means controlled by said latch for preventing suchmovement of said tripping element in response to such no--voltconditions when said latch is at its normal non-latching position andfor permitting such movement when said latch is latching said actuatingelement at its operative position, said tripping element, at its normalposition, being located to engage and retain one end of said lever, uponsaid actuating element being moved from its inoperative to its operativeposition, whereby the other end of said lever is moved, and said otherend being located to engage said switch element by such movement andconvey it to the switch closing position, and said tripping element,upon moving to the tripping position, disengaging and releasing thefirst-named end of said lever, whereby said switch element is re= leasedby said other end and returned by its bias ing means to said switchopening position.

7. An electric switch mechanism comprising an actuating element movableto an operative position and returnable to a non-operative position,

means biasing said actuating element to said nonoperative position, amanually releasable latch for automatically latching said actuatingelement at said operative position, a switch element movable along agiven path in one direction to a switch closing position and in theother direction to a switch opening position, means biasing said switchelement to said switch opening position, transmission means wherebymovement of said actuating element to said operative position eifectsmovement of said switch element to said switch closing position, ano-volt armature, a winding for said no-volt armature in the circuitcontrolled by said switch, said winding when energised maintaining saidarmature at an attracted position, means biasing said no-volt armatureto the non-attracted position, means for tripping said transmissionmeans in response to movement of said no-volt armature to thenon-attracted po= sition, and thereby permitting said switch element toreturn to the switch-opening position, and means controlled by saidlatch for preventing movement of said no-volt armature to thenonattracted position when said latch is at its normal non-latchingposition and for permitting such movement when said latch is latchingsaid actu ating element at said operative position.

8. An electric switch mechanism comprising an actuating element movableto an operative position and returnable to a non-operative position,means biasing said actuating element to said non-operative position, amanually releasable latch for automatically latching said actuatingelement at said operative position, a switch element movable along agiven path in one direction 10 to a switch, closing position and in theother direction to a switch opening, position, means biasing said switchelement to said switch opening position, transmission means wherebymovement ofsaid actuating element to said operative position effectsmovement of said switch element to said switch closing position, awinding'in the circuit controlled by said switch, a no-voltiarmature forsaid winding having'an attracted and a non-attracted position and biasedto its nonattracted position, an overload'armature for'isaid windinghaving an attracted and a non-attracted position and biased to itsnon-attracted position,

winding whenncrmally energised maintaining said no-volt armature at itsattracted position and leaving said overload armature at itsnon-attracted position, and, when energised by overload, moving saidoverload armature to the attracted position, means for trippingsaid'transmission means in response to movement'of said no-volt armatureto the non-attracted position or movement of said overload armature tothe attracted position, and thereby permitting said switch element toreturn to the switch opening position, and means controlled by saidlatch for preventing movement of said nc-volt armature to thenon-attracted position when said latch is at its normal non-latchingposition, and for permitting such movement when said latch is latchingsaid actuating element at its latching position, said last-named meansin no circumstances preventing movement of said overload armature to itsattracted position.

9. An electric switch mechanism comprising an actuating element movableto an operative position and returnable to a non-operative position,means biasing said actuating element to said non-operative position, amanually releasable latch for automatically latching said actuatingelement at said operative position, a switch element movable along agiven path in one direction to a switch closing position and'in theother direction to a switch opening position, means biasing said switchelement to said switch opening position, transmission means wherebymovement of said actuating element to said operative position effectsmovement of said switch element to said switch closing position, awinding in the circuit controlled by said switch, a no-volt armature forsaid winding having an attracted and a non-attracted position and biasedto its nonattracted position, an overload armature for said windinghaving an attracted and a non-attracted position and biased to itsnon-attracted position, said winding when normally energised maintainingsaid no-volt armature at its attracted position and leaving saidoverload armature at its non-attracted position, and, when energised byoverload, moving said overload armature to the attracted position, atripping element having a normal position and a tripping position, saidtripping element, when at its tripping position tripping saidtransmission, means and thereby permitting said switch element to returnto the switch opening position, means whereby move ment of said no-voltarmature to the non-attracted position or movement of said overloadwinding to the attracted position, efiects movement of said trippingelement to the tripping position and means controlled by said latch forpreventing movement of said no-volt armature to the non-attractedposition when said latch is at its normal non-latching position, and forpermitting such movement when said latch is latching said actuatinelement at its latching position,

said last-named means in no circumstances preventing movement of saidoverload armature to its attracted position.

10. An electrical switch mechanism comprising a switch element movablein one direction to a switch-closing position and in the other directionto a switch-opening position, means biasing said switch element to saidswitch opening position, an actuating element movable to an operativeposition and returnable to a non-operative position, transmission meanswhereby movement of said actuating element to said operative positioneffects movement of said switch element to said switch closing position,a winding in the circuit controlled by said switch, a no-volt armaturefor said winding having an attracted and a non-attracted position andbiased to its nonattracted position, an overload armature for saidwinding having an attracted and a non-attracted position and biased toits non-attracted position,

said winding when normally energised maintaining said no-volt armatureat its attracted position and leaving said overload armature at itsnon-attracted position, and when energised by overload, moving saidoverload armature to the attracted position, a tripping element having aposition for tripping said transmission means, said tripping elementbeing actuated to the tripping position by movement of said no-voltarmature to the non-attracted position or movement of said overloadarmature to the attracted position and thereby permitting said switchelement to return to the switch-opening position, a separate holdingelement, and an interlock between said actuating element and saidholding element whereby said holding element engages said novoltarmature and holds it at the attracted position for all positions ofsaid actuating element except said operative position and releases saidno-volt armature at said operative position of said actuating element,said holding element at no time obstructing movement of said overloadarmature to its attracted position.

11. An electric switch mechanism comprising an actuating element movableto an operative position and returnable to a non-operative position,means biasing said actuating element to said non-operative position, amanually releasable latch for automatically latching said actuatingelement at said operative position, a switch element movable along agiven path in one direction to a switch closing position and in theother direction to a switch opening position. means biasing said switchelement to said switch opening position, transmission means wherebymovement of said actuating element to said operative position efiectsmovement of said switch element to said switch closing position, awinding in the circuit controlled by the switch, a no-volt platearmature at one end of said winding biased to a non-attracted positionaway from said winding, an overload plunger armature within said windingbiased to a non-attracted position in the opposite direction to said no-volt plate armature, said winding, when normally energised maintainingsaid no-volt armature in opposition to its bias at an attracted positionand leaving said overload plunger armature at its non-attractedposition, and when energised by overload moving said overload plungerarmature through an opening in said no-volt plate armature to anattracted position, a tripping element having a normal position and atripping position, said tripping element, when at its tripping positiontripping said transmission means and thereby permitting said switchelement to return to the switch opening position, means whereby, eithersaid no-volt plate armature in moving to the non-attracted position orsaid overload plunger armature in moving to the attracted positionengages said tripping element and moves it to the tripping position, andmeans controlled by said latch for preventing movement of said no-voltarmature to the non-attracted position, when said latch is at its normalnonlatching position, and for permitting such movement when said latchis latching said actuating element at its latching position, saidlast-named means in no circumstances preventing movement of saidoverload armature to its attracted position.

12. An electrical switch mechanism as claimed in claim 10, comprising apivoted element constituting said interlock, said pivoted element havinga first position at which it holds said holding element at the positionfor holding said no-volt armature at the attracted position, and asecond position at which it releases said holding element, and meansbiasing said pivoted element to said second position, said actuatingelement engaging said pivoted element to hold the same at said firstposition at all positions of said actuating element except saidoperative position and to permit said pivoted element to move under saidbias to said second position at said operative position of saidactuating element.

13. An electrical switch mechanism as claimed in claim 12, wherein saidactuating element is formed with a shoulder and said pivoted element inmoving to said second position engages said shoulder to obstruct returnof said actuating element to its non-operative position.

FREDERICK JAMES PAVITI.

REFERENCES ClTED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 986,708 Greene Mar. 14, 19111,292,651 Rippl Jan. 28, 1919 2,431,886 Pavitt Dec. 2, 194'? 2,483,645Kitman Oct. 4, 1949 FOREIGN PATENTS Number Country Date 814,480 FranceMar. 22, 1937

